| RRT | random response technique; Registered Respiratory Therapist; relative retention time |
|---|---|
| RTR | Recreational Therapist, Registered; red blood cell turnover rate; retention time ratio |
| Tr | radiologic half-life; retention time |
| WR | Wassermann reaction; water retention; weakly reactive; weak response; whole response; wiping reactio... |
| WRC | washed red cells; water retention coefficient |